Favourite manner woven in is fixed (9)
I believe the answer is:
permanent
'is fixed' is the definition.
(I've seen this before)
'favourite manner woven in' is the wordplay.
'favourite' becomes 'pet' (synonyms).
'woven' is an anagram indicator.
'in' means one lot of letters goes inside another.
'manner' is an anagram of 'rmanen'.
'pet' placed around 'rmanen' is 'PERMANENT'.
(Other definitions for permanent that I've seen before include "Fixed" , "not expected to change" , "Like some secretaries" , "Lasting indefinitely" , "Lasting; not temporary" .)