Set back, having raised sail? (7)
I believe the answer is:
regular
'set' is the definition.
(thesaurus)
'back having raised sail?' is the wordplay.
'back' becomes 'rear' (something's rear is its back).
'having' is an insertion indicator.
'raised' is a reversal indicator (going up in a down clue).
'sail?' becomes 'lug' (lug is a kind of sail).
'lug' backwards is 'gul'.
'rear' enclosing 'gul' is 'REGULAR'.
(Other definitions for regular that I've seen before include "Normal, steady" , "Occurring at fixed intervals" , "Usual, customary" , "Steady, in a fixed order" , "Steady, even" .)