A card that's useful in digs (5)
I believe the answer is:
spade
'a card' is the definition.
(the spades are a playing card suit)
'useful in digs' is the wordplay.
I cannot quite understand how this works, but
'digs' could be 'pad' (synonyms) and 'pad' is located in the answer.
The remaining letters 'se' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
'that's' is the link.
Can you help me to learn more?
(Other definitions for spade that I've seen before
include
"Black leaf-shaped symbol on playing card"
,
"Shovel-like tool"
,
"10