Worried gymnast, somewhat nervous (4)
I believe the answer is:
edgy
'nervous' is the definition.
(synonyms)
'worried gymnast somewhat' is the wordplay.
'somewhat' indicates the answer is hidden within the clue.
'EDGY' is hidden in the letters of 'worried gymnast'.
(Other definitions for edgy that I've seen before include "Extremely" , "Overstrung" , "In a tense state" , "Visibly nervous" , "Jittery" .)