Put to the test by surprise party absorbing barman (3,1,2)
I believe the answer is:
had a go
'absorbing barman' is the definition.
I know nothing about this answer so I cannot tell whether this works.
'put to the test by surprise party' is the wordplay.
'put' indicates putting letters inside.
'to the test by' becomes 'ag' (I am not sure about this - if you are sure you should believe this answer much more).
'surprise' becomes 'ha' (I've seen this in other clues).
'party' becomes 'do' (do is a kind of party).
'ha'+'do'='hado'
'ag' put into 'hado' is 'HAD A GO'.
Can you help me to learn more?
(Other definitions for had a go that I've seen before include "Tried" , "Made an attempt" .)