In tears over dead squirrels etc (7)
I believe the answer is:
rodents
'squirrels etc' is the definition.
'in tears over dead' is the wordplay.
'in' indicates putting letters inside.
'tears' becomes 'rents' (rent is a kind of tear).
'over dead' becomes 'od' (this might be a standard abbreviation of which I'm unaware).
'rents' going around 'od' is 'RODENTS'.
Can you help me to learn more?
(Other definitions for rodents that I've seen before include "Animals that gnaw" , "Eg, mice" , "Rats, mice, hamsters" , "Mice, squirrels etc" , "Rats and mice, say" .)