Seldom seen in Gloucester area (4)
I believe the answer is:
rare
'seldom seen' is the definition.
(something seldom seen is seen rarely)
'in gloucester area' is the wordplay.
'in' says the answer is hidden in the clue.
'RARE' can be found hidden inside 'gloucester area'.
(Other definitions for rare that I've seen before include "Scarcely seen" , "Bloody (of steaks)" , "Very scarce like valuable antique" , "Scarce as hen's teeth!" , "not often spotted" .)