Broken lens, frames: glasses for free (6)
I believe the answer is:
loosen
'free' is the definition.
(I've seen this before)
'broken lens frames glasses' is the wordplay.
'broken' is an anagram indicator.
'frames' means one lot of letters goes inside another.
'glasses' becomes 'OO' (OO looks like spectacles).
'lens' with letters rearranged gives 'lsen'.
'lsen' going around 'oo' is 'LOOSEN'.
'for' is the link.
(Other definitions for loosen that I've seen before include "Relax the tension" , "Untie, relax" , "Undo, make less tight" , "Undo a little" , "relax or tear apart" .)