One supporting swine with swine supporting them initially (7)

I believe the answer is:
trotter
'one supporting swine' is the definition.
The definition and answer can be both animals as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
'swine supporting them initially' is the wordplay.
'swine' becomes 'rotter'.
'supporting' is a charade indicator (letters next to each other) (in a down clue, some letters go below others).
'initially' suggests taking the first letters.
The initial letter of 'them' is 't'.
'rotter' after 't' is 'TROTTER'.
'with' acts as a link.
Can you help me to learn more?
(Other definitions for trotter that I've seen before include "Briskly moving horse - pig's foot" , "Steady horse; pig's foot" , "Pig's paw" , "bit of a pig" , "Harnessed mount" .)
