Why we had such a dull day? (5)
I believe the answer is:
cloud
'dull day?' is the definition.
'cloud' can be an answer for 'dull' (thesaurus). I am unsure of the 'day?' bit.
'why we had such a' is the wordplay.
I cannot really understand how this works, but
'had' could be 'd' (in contractions e.g. 'I'd', 'you'd' etc) and 'd' is located in the answer.
The remaining letters 'clou' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for cloud that I've seen before include "Make less transparent" , "Make less clear" , "Obscure" , "Become gloomy" , "Visible vapour in sky" .)