Learn lines for speaking (8)
I believe the answer is:
converse
'speaking' is the definition.
(thesaurus)
'learn lines' is the wordplay.
'learn' becomes 'con' (synonyms).
'lines' becomes 'verse' (lines of poetry).
'con'+'verse'='CONVERSE'
'for' acts as a link.
(Other definitions for converse that I've seen before include "Talk together" , "Talk - opposite" , "speak" , "discuss" , "Discourse" .)