Initially retired, Michael Caine’s having to work: one goes over lines (9,5)
I believe the answer is:
vanishing cream
'one goes over lines' is the definition.
(cosmetic over lines in skin)
'initially retired michael caine's having to work' is the wordplay.
'initially' indicates taking the first letters.
'to work' indicates anagramming the letters (letters worked into a new order).
The first letters of 'retired michael' is 'rm'.
'rm'+'caines'+'having'='rmcaineshaving'
'rmcaineshaving' is an anagram of 'VANISHING CREAM'.
(Other definitions for vanishing cream that I've seen before include "Brain Drain" , "foundation?" , "Cosmetic" .)