Creature seen in far lough now and then (4)
I believe the answer is:
frog
'creature' is the definition.
(frog is a kind of creature)
'far lough now and then' is the wordplay.
'now and then' means one should take alternating letters (letters taken on a regular basis, now and then).
'far'+'lough'='farlough'
The alternating letters of 'farlough' are 'FROG'.
'seen in' acts as a link.
(Other definitions for frog that I've seen before include "Croaker?" , "Adult tadpole" , "Grown-up tadpole" , "Amphibious neighbour of 12?" , "Common amphibian" .)