Husband in march shows fibre (6)
I believe the answer is:
thread
'fibre' is the definition.
(I've seen this before)
'husband in march' is the wordplay.
'husband' becomes 'h' (abbreviation).
'in' indicates putting letters inside.
'march' becomes 'tread' (I've seen this before).
'h' placed into 'tread' is 'THREAD'.
'shows' is the link.
(Other definitions for thread that I've seen before include "Train of thought - screw feature" , "The rib going around a screw" , "Twine" , "Dearth (anag)" , "What sewer takes" .)