Bowled in an international under the most favourable conditions (2,4)
I believe the answer is:
at best
'under the most favourable conditions' is the definition.
(I've seen this before)
'bowled in an international' is the wordplay.
'bowled' becomes 'b' (cricket abbreviation).
'in' means one lot of letters goes inside another.
'an' becomes 'a'.
'international' becomes 'test' (I've seen this before).
'a'+'test'='atest'
'b' going within 'atest' is 'AT BEST'.
(Other definitions for at best that I've seen before include "In the most favourable outcome" , "In the optimum situation" , "Taking the most hopeful view" , "Making every allowance" , "In the most optimistic scenario" .)