Cyril's lost for words (5)
I believe the answer is:
lyric
'words' is the definition.
(synonyms)
'cyril's lost' is the wordplay.
'lost' is an anagram indicator.
'cyril' anagrammed gives 'LYRIC'.
'for' acts as a link.
(Other definitions for lyric that I've seen before include "something to sing about? On the contrary" , "in musical" , "Words to a song" , "Of poetry that expresses thoughts and feelings" , "Text of a popular song" .)