I'm not sure about the shocking event but I think you are
Each line indicates
Wordplay the word defined in the second part surrounds amp to give the word defined in the first part.
When I'm all over the place - give me a yelling
Rampant - to rant is to speak or shout at length in an angry, impassioned way.
When I need hair washing - give me a frightening
Shampoo - shoo is a word said to frighten or drive away a person or animal.
When I need a clutch - give me soft singing
Clamp - not sure about this one but the second part could refer to the singer CL
When I need an aromatic - give me a whole county
Samphire - where a county is equivalent to a shire.
When I need a little taking - give me a carry
Sampling - a sling is a flexible strap or belt used in the form of a loop to support or raise a hanging weight.
When I'm just getting started - give me a finger
Ramping - ramping as in "ramping up".
When I want to get wetter - give me a place to hide
When I need contraceptives - give me a lot
Tampon - the contraceptive definition doesn't match here, although ton indicates a lot and I think this might be what OP was going for.
When I need to fill up - give me a boost
Jampack - a very clever one, jampack means to crowd and jack is a synonym for boost.
When I need an explosive in mixture - give me after shot
Firedamp - a combustible gas, fired may be the past tense of fire, synonym for shoot.
When I need to word it sharply - give me a crazy one
Lampoon - a loon is a crazy or foolish person.
When I need a firm hold - give me a lasting embrace
After I dropped drinking and Cheerios (too bad!), I heard of a shocking event.
Who am I, and what is it?
Not sure about this part, I feel like there is some anagramming and wordplay with the words 'amp', 'cheerios' and possibly 'drinking'. The best I could come up with was KIM CHAPIRON RESIGNED although there are some interesting words in the subanagrams such as IMPEACHED, IMPRISONED and CHARGED which might also be involved.