Touched iron last, losing heart (4)
I believe the answer is:
felt
'touched' is the definition.
(feeling is a kind of touching)
'iron last losing heart' is the wordplay.
'iron' becomes 'fe' (Fe is the chemical symbol for iron).
'losing heart' says to hollow out the word (remove centre letters).
'last' with its middle removed is 'lt'.
'fe'+'lt'='FELT'
(Other definitions for felt that I've seen before include "Material - perceived by touch" , "Sensed; fibre cloth" , "Touched the matted fabric" , "examined by touch" , "Handled - material" .)