One Guinness female companions conceal (4)
I believe the answer is:
alec
'one guinness' is the definition.
(I've seen this in another clue)
'female companions conceal' is the wordplay.
'conceal' indicates a hidden word.
'ALEC' is hidden in the letters of 'female companions'.
(Other definitions for alec that I've seen before include "Smart man?" , "Sir -- Guinness, actor" , "Smart chap" , "Guinness (a smart lad?)" , "Smart ..., he thinks he knows everything" .)