May help in building a house or destroying it (6)
I believe the answer is:
mortar
'may help in building' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.
'a house or destroying it' is the wordplay.
I cannot quite understand how this works, but
'a' is found in the answer.
'or' is found in the answer.
'it' could be 't' (abbreviation. e.g. in 'tis) and 't' is located in the answer.
The remaining letters 'mr' is a valid word which might be clued in a way I don't see.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for mortar that I've seen before include "A short cannon for firing shells" , "Artillery weapon - building mixture - vessel with a pestle" , "Brick bonder; weapon" , "may be set into wall" , "Bomb-firing weapon" .)