Glaswegian puts son to bed (4)
I believe the answer is:
scot
'glaswegian' is the definition.
(I've seen this in another clue)
'son to bed' is the wordplay.
'son' becomes 's' (genealogical abbreviation for son).
'to' means one lot of letters go next to another.
'bed' becomes 'cot' (cot is a type of bed).
's'+'cot'='SCOT'
'puts' acts as a link.
(Other definitions for scot that I've seen before include "UK northerner" , "Payment" , "Highlander perhaps" , "Someone from north of the border?" , "levy, once" .)