Grumpy person, in third pub on the crawl, turned up? (4)
I believe the answer is:
crab
'grumpy person' is the definition.
(I've seen this in another clue)
'third pub on the crawl turned up?' is the wordplay.
'third pub' becomes 'b' (crd letter of 'pub').
'on' says to put letters next to each other.
'the crawl' becomes 'arc' (I can't justify this - if you can you should give a lot more credence to this answer).
'turned up?' says the letters should be written in reverse.
'arc' backwards is 'cra'.
'b' after 'cra' is 'CRAB'.
'in' acts as a link.
Can you help me to learn more?
(Other definitions for crab that I've seen before include "A crustacean; type of apple" , "Scuttling crustacean" , "one is a fiddler" , "Fiddler, perhaps" , "One may be caught" .)