Nicer detectives, not able to see clearly (7)
I believe the answer is:
discern
'see clearly' is the definition.
'discern' can be an answer for 'see' (I've seen this before). I am not certain of the 'clearly' bit.
'nicer detectives not able' is the wordplay.
I cannot quite see how this works, but
'detectives' could be 'dis' (Detective Inspectors, DIs) and 'dis' is found in the answer.
This explanation may well be incorrect...
'to' acts as a link.
Can you help me to learn more?
(Other definitions for discern that I've seen before include "Recognise, find out" , "Espy" , "Perceive - distinguish" , "spot" , "See" .)