Fox seen in Stroud every now and again (3)
I believe the answer is:
tod
'fox' is the definition.
(historic term)
'stroud every now and again' is the wordplay.
'every now and again' means one should take alternating letters.
The alternate letters of 'stroud' are 'TOD'.
'seen in' is the link.
(Other definitions for tod that I've seen before include "Fox" , "One's alone on this" , "Sly person" , "Former English weight for wool - dot it" , "If you're on it, you're on your own" .)