Paddy infiltrating soldiers’ defences (8)

I believe the answer is:

parapets

'defences' is the definition.
(parapet is a kind of defence)

'paddy infiltrating soldiers'' is the wordplay.
'paddy' becomes 'pet' (I've seen this in other clues).
'infiltrating' means one lot of letters goes inside another.
'soldiers'' becomes 'paras' (para is a kind of soldier).
'pet' placed inside 'paras' is 'PARAPETS'.

(Another definition for parapets that I've seen is " Low protective walls along edges of roofs or balconies".)

I've seen this clue in The Sunday Times and The Times.

Want a hint initially instead of a full solution? Install my app