Crossword Genius

A poor innings by chap lacking a partner (1,6,3)

Ross

I believe the answer is:

a single man

I'm a little stuck... Click here to teach me more about this clue!

'lacking a partner' is the definition.
I know nothing about this answer so I cannot tell whether this works.

'a poor innings by chap' is the wordplay.
'poor innings' becomes 'single' (I can't explain this - if you can you should give a lot more credence to this answer).
'by' means one lot of letters go next to another.
'chap' becomes 'man' (chap can mean a man).
'a'+'single'+'man'='A SINGLE MAN'

Can you help me to learn more?

I've seen this clue in The Guardian.
Want a hint initially instead of a full solution? Install my app