Conservative grip in decline? (11)
I believe the answer is:
contraction
'decline?' is the definition.
(contraction can mean decline or shrinkage)
'conservative grip' is the wordplay.
'conservative' becomes 'con' (abbreviation for Conservative).
'grip' becomes 'traction' (synonyms).
'con'+'traction'='CONTRACTION'
'in' is the link.
(Other definitions for contraction that I've seen before include "Isn't, for instance" , "Process of size reduction" .)