Cyril managed to find a lake poetic (7)
I believe the answer is:
lyrical
'poetic' is the definition.
(I've seen this before)
'cyril managed to find a lake' is the wordplay.
'managed' is an anagram indicator.
'to find' is a charade indicator (letters next to each other).
'lake' becomes 'L' (geographical abbreviation).
'cyril' is an anagram of 'lyric'.
'lyric'+'a'+'l'='LYRICAL'
(Other definitions for lyrical that I've seen before include "it can be waxed" , "Enthusiastic - expressing the writer's feelings" , "carried away" , "To wax - is to enthuse" , "Relating to song's words" .)