Lock shed with no external features, in line with sporting regulations (4)
I believe the answer is:
oche
'line with sporting regulations' is the definition.
'oche' can be an answer for 'line' (I've seen this before). I'm not sure about the 'with sporting regulations' bit.
'lock shed with no external features' is the wordplay.
I cannot really understand how this works, but
'no' could be 'o' (resembles 0 - 'no' can mean 'zero') and 'o' is found within the answer.
The remaining letters 'che' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
'in' acts as a link.
Can you help me to learn more?
(Other definitions for oche that I've seen before include "Line where dart thrower stands" , "The mark at darts" , "Dart-throwing line" , "Heavy African knife" , "Line not to be crossed" .)