Perhaps glasses of whiskey are drunk following verbal agreement (7)
I believe the answer is:
eyewear
'perhaps glasses' is the definition.
'eyewear' can be an answer for 'glasses' (I've seen this before). I am not certain of the 'perhaps' bit.
'whiskey are drunk following verbal agreement' is the wordplay.
I cannot quite see how this works, but
'whiskey' could be 'w' (alpha bravo charlie delta ...) and 'w' is found within the answer.
an anagram of 'are' is 'ear' which is within the answer.
'verbal agreement' could be 'eye' (sounds like 'aye') and 'eye' is found in the answer.
This accounts for all the letters.
This explanation may well be incorrect...
'of' is the link.
Can you help me to learn more?
(Other definitions for eyewear that I've seen before include "Eg, spectacles, contact lenses" , "viewers' protection" , "glasses" , "reading aids" .)