Young bird shot with catapult (7)
I believe the answer is:
gosling
'young bird' is the definition.
(I've seen this before)
'shot with catapult' is the wordplay.
'shot' becomes 'go' (both can mean an attempt).
'with' means one lot of letters go next to another.
'catapult' becomes 'sling' (synonyms).
'go'+'sling'='GOSLING'
(Other definitions for gosling that I've seen before include "Young waterbird" , "Little bird" , "Young goose" , "Young bird" .)