Hostile force made up story (6)
I believe the answer is:
frosty
'hostile' is the definition.
Both the answer and definition are adjectives. Perhaps you can see an association between them that I can't see?
'force made up story' is the wordplay.
'force' becomes 'F' (symbol used in Physics e.g. f=ma).
'made up' indicates an anagram.
'story' anagrammed gives 'rosty'.
'f'+'rosty'='FROSTY'
Can you help me to learn more?
(Other definitions for frosty that I've seen before include "Lacking in warmth" , "Chilly in attitude, like musical snowman" , "Cold and unfriendly (glance or reception?)" , "Icy cold" , "showing little enthusiasm" .)