Spot big feline protecting old feline (8)
I believe the answer is:
location
'spot' is the definition.
(I've seen this before)
'big feline protecting old feline' is the wordplay.
'big feline' becomes 'lion' (lion is a kind of feline. I am not sure about the 'big' bit.).
'protecting' indicates putting letters inside (inserted letters are held or protected).
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'feline' becomes 'cat' (cat is a kind of feline).
'o'+'cat'='ocat'
'lion' placed around 'ocat' is 'LOCATION'.
Can you help me to learn more?
(Other definitions for location that I've seen before include "Spot - where films may be shot" , "Position,place" , "Whereabouts, position" , "Place, position" , "Place, site" .)