Dare stray, shackled by proposal for self-restraint (10)
I believe the answer is:
moderation
'self-restraint' is the definition.
(I've seen this before)
'dare stray shackled by proposal' is the wordplay.
'stray' indicates anagramming the letters.
'shackled by' is an insertion indicator (I've seen this in other clues).
'proposal' becomes 'motion' (motion is a kind of proposal).
'dare' is an anagram of 'dera'.
'dera' put within 'motion' is 'MODERATION'.
'for' acts as a link.
(Other definitions for moderation that I've seen before include "self-control" , "Avoidance of excess" , "Avoidance of extremes" , "self-restraint" , "avoids extremes" .)