At a loose end and not dressed yet? (7,2)

'at a' is the definition.
I don't know anything about this answer so I can't tell whether it can be defined by this definition.

'loose end and not dressed yet?' is the wordplay.
'loose' becomes 'open' ('open' can be a synonym of 'loose').
'end' suggests removing the centre (I've seen 'ends' mean this).
'and' says to put letters next to each other (I've seen this in other clues).
'dressed yet?' becomes 'hing' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'open' with its middle removed is 'on'.
'not'+'hing'='nothing'
'on' put after 'nothing' is 'NOTHING ON'.

Can you help me to learn more?