Charlie and son cover up smell for friends (5)

'friends' is the definition.
(chum is a kind of friend)

'charlie and son cover up smell' is the wordplay.
'charlie' becomes 'C' (phonetic alphabet: alpha, bravo, charlie etc.).
'and' means one lot of letters go next to another.
'son' becomes 's' (genealogical abbreviation for son).
'cover up' indicates putting letters inside.
'smell' becomes 'hum' (something with a bad smell is 'humming').
'c'+'s'='cs'
'cs' placed around 'hum' is 'CHUMS'.

'for' is the link.