Novice with lager going round guy's first pub (8)
I believe the answer is:
beginner
'novice' is the definition.
(synonyms)
'lager going round guy's first pub' is the wordplay.
'lager' becomes 'beer' (I've seen this in another clue).
'going round' is an insertion indicator (some letters go around others).
'guy's first' becomes 'g' (1st letter of 'guy').
'pub' becomes 'inn' (an inn is a type of pub).
'g'+'inn'='ginn'
'beer' going around 'ginn' is 'BEGINNER'.
'with' acts as a link.
(Other definitions for beginner that I've seen before include "Starter" , "new recruit, perhaps" , "Fresher" , "inexperienced person" , "Tyro, novice" .)