Loom I repair without pressure (6)
I believe the answer is:
impend
'loom' is the definition.
(I've seen this before)
'i repair without pressure' is the wordplay.
'repair' becomes 'mend' (synonyms).
'without' means one lot of letters goes inside another ('without' can be similar in meaning to 'outside').
'pressure' becomes 'p' (abbreviation).
'mend' placed around 'p' is 'mpend'.
'i'+'mpend'='IMPEND'
(Other definitions for impend that I've seen before include "(Of a bad thing) loom" , "appearing to be imminent" , "Be looming" , "Threaten - be about to happen" , "Be about to take place" .)