He will run away when the sun comes out (7)
I believe the answer is:
snowman
'out' is the definition.
Although both the answer and definition are singular nouns, I don't see how they can define each other.
'he will run away when the sun' is the wordplay.
I cannot quite see how this works, but
'he' could be 'man' (I've seen this in another clue) and 'man' is found in the answer.
'sun' could be 's' (abbreviation) and 's' is found in the answer.
The remaining letters 'now' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
'comes' acts as a link.
Can you help me to learn more?
(Other definitions for snowman that I've seen before include "Winter figure" , "Impermanent figure" , "Cold character" , "Frosty the . . . . . . . (children's song)" , "wintry figure?" .)