Language making sober actor struggle (5-5)
I believe the answer is:
serbo-croat
'language' is the definition.
(I've seen this before)
'making sober actor struggle' is the wordplay.
'making' is an anagram indicator.
'struggle' is an anagram indicator (letters move around or struggle).
'sober' anagrammed gives 'serbo'.
'actor' is an anagram of 'croat'.
'serbo'+'croat'='SERBO-CROAT'
(Other definitions for serbo-croat that I've seen before include "European" , "language" .)