Terribly overactive with no right being reminiscent (9)
I believe the answer is:
evocative
'reminiscent' is the definition.
('evocative' can be a synonym of 'reminiscent')
'terribly overactive with no right' is the wordplay.
'terribly' indicates an anagram.
'with no' suggests deleting specific letters.
'right' becomes 'r' (common abbreviation).
'overactive' with 'r' removed is 'oveactive'.
'oveactive' is an anagram of 'EVOCATIVE'.
'being' is the link.
(Other definitions for evocative that I've seen before include "Tending to call up, say memories" , "Bringing out strong feelings" , "Reminiscent, resonant" , "Haunting" , "Calling up strong images" .)