Man slammed the cottage's rear door (8)
I believe the answer is:
theodore
'man' is the definition.
(I've seen this before)
'slammed the cottage's rear door' is the wordplay.
'slammed' indicates anagramming the letters.
'rear' suggests the final letters (the back of the word).
The final letter of 'cottage' is 'e'.
'the'+'e'+'door'='theedoor'
'theedoor' with letters rearranged gives 'THEODORE'.
(Other definitions for theodore that I've seen before include "Man" , "... Roosevelt" , "ex-president was named thus" .)