A way to hold one in five in a disapproving look (6)
I believe the answer is:
squint
'a disapproving look' is the definition.
'a way to hold one in five' is the wordplay.
'a way' becomes 'st'.
'to hold' means one lot of letters goes inside another.
'one in five' becomes 'quin' (I've seen this before).
'st' enclosing 'quin' is 'SQUINT'.
'in' is the link.
(Other definitions for squint that I've seen before include "Misalignment of eye" , "Look with the eyes partly closed" , "Quick look" , "Fault with eye" , "Strabismus" .)