A student pursuing new topic of sight (7)
I believe the answer is:
optical
'of sight' is the definition.
(optical means relating to sight)
'a student pursuing new topic' is the wordplay.
'student' becomes 'l' (as in L-plates for learner drivers).
'pursuing' is a charade indicator (letters next to each other).
'new' indicates anagramming the letters.
'topic' is an anagram of 'optic'.
'a'+'l'='al'
'al' put after 'optic' is 'OPTICAL'.
(Other definitions for optical that I've seen before include "Relating to the eye" , "Using visible light" , "Topical (anag.)" , "Sort of illusion" , "connected to light" .)