Tough guys losing money and temper (6)
I believe the answer is:
harden
'temper' is the definition.
('harden' can be a synonym of 'temper')
'tough guys losing money' is the wordplay.
'tough' becomes 'hard' ('hard' can be a synonym of 'tough'**).
'guys' becomes 'men'.
'losing' suggests deleting specific letters.
'money' becomes 'm' (abbreviation in economics).
'men' with 'm' taken out is 'en'.
'hard'+'en'='HARDEN'
'and' is the link.
(Other definitions for harden that I've seen before include "Become less sympathetic" , "Become firm and solid" , "Temper, steel say" , "Set; become tougher" , "Steel oneself" .)