Old soldiers possibly filling one with pride (6)
I believe the answer is:
legion
'old soldiers' is the definition.
'legion' can be an answer for 'soldiers' (I've seen this before). I am not certain of the 'old' bit.
'possibly filling one with pride' is the wordplay.
'possibly' becomes 'eg' (for example).
'filling' is an insertion indicator.
'one with pride' becomes 'lion' (I've seen this in other clues).
'eg' inserted into 'lion' is 'LEGION'.
Can you help me to learn more?
(Other definitions for legion that I've seen before include "Large unit of the old Roman army" , "A great number in the Roman military unit" , "Large military force" , "Vast multitude" , "Roman battalion" .)