Relating to sight seen in abandoned coalpit (7)
I believe the answer is:
optical
'relating to sight' is the definition.
(I've seen this before)
'abandoned coalpit' is the wordplay.
'abandoned' is an anagram indicator.
'coalpit' is an anagram of 'OPTICAL'.
'seen in' is the link.
(Other definitions for optical that I've seen before include "Topical (anag.)" , "Working with light" , "Capitol (anag.)" , "Relating to vision and light" , "Relating to the eye" .)