Staff in good Post Office entertained by funny fella (8)
I believe the answer is:
flagpole
'staff' is the definition.
(I know that Flagpole is a type of staff)
'good post office entertained by funny fella' is the wordplay.
'good' becomes 'g' (abbreviation).
'post office' becomes 'po' (abbreviation).
'entertained by' indicates putting letters inside (inserted letters are hosted or entertained).
'funny' is an anagram indicator.
'g'+'po'='gpo'
'fella' is an anagram of 'flale'.
'gpo' put into 'flale' is 'FLAGPOLE'.
'in' is the link.
(Other definitions for flagpole that I've seen before include "standard-bearer" , "means to raise standard" , "Support for banner." , "Upholder of standards" , "On which standard flies" .)