Picture of one male, mature (5)
I believe the answer is:
image
'picture' is the definition.
(I know that picture can be written as image)
'one male mature' is the wordplay.
'one' becomes 'i' (Roman numeral).
'male' becomes 'm' (common abbreviation).
'mature' becomes 'age' (synonyms).
'i'+'m'+'age'='IMAGE'
'of' acts as a link.
(Other definitions for image that I've seen before include "Likeness U symbol" , "Iconic representation" , "Portrait, picture" , "Likeness or mental picture" , "Optical counterpart in mirror" .)