A bit of help: one across is a house (7)
I believe the answer is:
hanover
'house' is the definition.
(I've seen this before)
'a bit of help one across' is the wordplay.
'a bit of' says to take the initial letters.
'one' becomes 'an' (I've seen this in other clues).
'across' becomes 'over' (synonyms).
The initial letter of 'help' is 'h'.
'h'+'an'+'over'='HANOVER'
'is a' is the link.
(Other definitions for hanover that I've seen before include "German town, and royal house" , "9 [HOUSE]" , "Royal house from 1727" , "Royal house from George I to Victoria" , "Royal house after Stuarts" .)