Loud rave, sick at heart and agitated (7)
I believe the answer is:
frantic
'agitated' is the definition.
('frantic' can be similar in meaning to 'agitated')
'loud rave sick at heart' is the wordplay.
'loud' becomes 'f' (A musical term).
'rave' becomes 'rant' ('rant' can be a synonym of 'rave').
'at heart' says to take the centre.
The centre of 'sick' is 'ic'.
'f'+'rant'+'ic'='FRANTIC'
'and' acts as a link.
(Other definitions for frantic that I've seen before include "having kittens" , "Distracted" , "Overwrought" , "Wildly agitated" , "not collected!" .)