Strong drink opponents love guzzling squash (8)
I believe the answer is:
espresso
'strong drink' is the definition.
(type of coffee drink)
'opponents love guzzling squash' is the wordplay.
'opponents' becomes 'es' (I've seen this in other clues).
'love' becomes 'o' (love means zero in tennis).
'guzzling' means one lot of letters goes inside another (I've seen this in other clues).
'squash' becomes 'press' (I've seen this in other clues).
'es'+'o'='eso'
'eso' placed around 'press' is 'ESPRESSO'.
(Other definitions for espresso that I've seen before include "Strong coffee made with steam machine" , "Italian-style coffee" , "that's stimulating" , "Seep Ross into the coffee" , "Coffee (S, not X)" .)