The cost of reduced life expectancy (3)
I believe the answer is:
fee
'the cost' is the definition.
(fee is a kind of cost)
'of reduced life expectancy' is the wordplay.
'of' indicates the answer is hidden within the clue.
'FEE' is hidden in the letters of 'reduced life expectancy'.
(Other definitions for fee that I've seen before include "Sum payable to, say, barrister" , "(Entry) charge" , "Amount paid for job" , "Cost" , "Money paid for professional services" .)