Before ten, mail unfortunately not dispatched? Tough (13)
I believe the answer is:
unsentimental
'tough' is the definition.
('unsentimental' can be similar in meaning to 'tough')
'before ten mail unfortunately not dispatched?' is the wordplay.
'before' is a charade indicator (letters next to each other).
'unfortunately' indicates an anagram.
'not dispatched?' becomes 'unsent' (I've seen this before).
'ten'+'mail'='tenmail'
'tenmail' anagrammed gives 'imental'.
'imental' after 'unsent' is 'UNSENTIMENTAL'.
(Other definitions for unsentimental that I've seen before include "Tough-minded" , "Eschewing tender emotions" , "Not given to excessively tender emotions" , "Showing no tender emotions" , "hard-nosed" .)