Timidity caught by ancient poetry (4,4)
I believe the answer is:
cold feet
'timidity' is the definition.
(I've seen this in another clue)
'caught by ancient poetry' is the wordplay.
'caught' becomes 'c' (cricket abbreviation).
'by' is a charade indicator (letters next to each other).
'ancient' becomes 'old' (similar in meaning).
'poetry' becomes 'feet' (poetic structures are made up of metric feet).
'c'+'old'+'feet'='COLD FEET'
(Other definitions for cold feet that I've seen before include "Apprehensiveness" , "Icy extremities for slang fear" , "Loss of courage or confidence" , "Lack of courage or confidence" , "You might have them if you're afraid to proceed" .)