A chap standing beside father, with a hat (6)
I believe the answer is:
panama
'hat' is the definition.
(I know that Panama is a type of hat)
'a chap standing beside father' is the wordplay.
'chap' becomes 'man' (chap can mean a man).
'standing' shows that the letters should be reversed in order (in a down clue, letters stand up).
'beside' says to put letters next to each other (I've seen this in other clues).
'father' becomes 'pa' (pa can mean dad or father).
'a'+'man'='aman'
'aman' in reverse letter order is 'nama'.
'nama' put after 'pa' is 'PANAMA'.
'with a' is the link.
(Other definitions for panama that I've seen before include "Man's hat" , "Central American country" , "Canal state; hat" , "Great American canal or tropical hat" , "Style of hat" .)