Maugham, oddly neglected, fashionable once more (5)
I believe the answer is:
again
'once more' is the definition.
('again' can be a synonym of 'once more')
'maugham oddly neglected fashionable' is the wordplay.
'oddly neglected' means one should take alternating letters.
'fashionable' becomes 'in' ('in' can be similar in meaning to 'fashionable').
The alternate letters of 'maugham' are 'aga'.
'aga'+'in'='AGAIN'
(Other definitions for again that I've seen before include "'Another time, once more (5)'" , "Ocne more" , "Furthermore" , "10 10 [AGAIN" , "second term" .)