Old poet in pandemic losing head (4)
I believe the answer is:
ovid
'old poet' is the definition.
(Roman poet)
'pandemic losing head' is the wordplay.
'pandemic' becomes 'covid' (covid-19 pandemic).
'losing head' means to remove the first letter.
'covid' with its first letter removed is 'OVID'.
'in' acts as a link.
(Other definitions for ovid that I've seen before include "Metamorphoses author" , "Vi, do read the Latin poet" , "Latin poet (Ars amatoria, Metamorphoses)" , "Old linesman" , "Roman poet N void (anag)" .)