Gigantic flying creature captures a minute male (7)
I believe the answer is:
mammoth
'gigantic' is the definition.
(synonyms)
'flying creature captures a minute male' is the wordplay.
'flying creature' becomes 'moth'.
'captures' means one lot of letters goes inside another.
'minute' becomes 'm' (abbreviation).
'male' becomes 'm' (common abbreviation).
'a'+'m'+'m'='amm'
'moth' placed around 'amm' is 'MAMMOTH'.
(Other definitions for mammoth that I've seen before include "Huge" , "Prehistoric woolly elephant" , "Extinct species of elephant" , "Extinct type of elephant" , "Extinct hairy elephant" .)