Has an adverse effect on the development of gimmicks (6)
I believe the answer is:
stunts
'gimmicks' is the definition.
The definition and answer can be both acts as well as being plural nouns.
Perhaps you can see a link between them that I don't see?
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for stunts that I've seen before include "Hinders the growth of, like tricks" , "hair-raising exploits" , "Prevents from growing properly" , "Exploits, feats" , "Prevents further development" .)