Bob has lorry mostly climbing? Yes, climbing (7)
I believe the answer is:
curtsey
'bob' is the definition.
(I've seen this before)
'lorry mostly climbing? yes climbing' is the wordplay.
'lorry' becomes 'truck' (I've seen this before).
'mostly' means to remove the last letter (most but not all of the word).
'climbing?' says the letters should be written in reverse (in a down clue, letters climb up).
'yes climbing' becomes 'sey' (I can't justify this - if you can you should give a lot more credence to this answer).
'truck' with its last letter taken off is 'truc'.
'truc' in reverse letter order is 'curt'.
'curt'+'sey'='CURTSEY'
'has' is the link.
Can you help me to learn more?
(Other definitions for curtsey that I've seen before include "Formal greeting, bob" , "Gesture of respect" , "Respectful greeting" , "Girl's bob" , "old form of obeisance" .)