Periods when male is restricted by obligations (5)
I believe the answer is:
times
'periods' is the definition.
(time is a kind of period)
'male is restricted by obligations' is the wordplay.
'male' becomes 'm' (common abbreviation).
'is restricted by' means one lot of letters goes inside another (I've seen this in other clues).
'obligations' becomes 'ties' (I've seen this in another clue).
'm' inserted within 'ties' is 'TIMES'.
'when' acts as a link.
(Other definitions for times that I've seen before include "Periods, ages" , "Thunderer?" , "Paper" , "Newspaper - X" , "Square in New York" .)