Unusual niche in training college at first for practical skill (7)

'practical skill' is the definition.
(US spelling of 'technique')

'unusual niche in training college at first' is the wordplay.
'unusual' is an anagram indicator.
'in' is an insertion indicator.
'at first' indicates taking the first letters.
The initial letters of 'training college' is 'tc'.
'niche' with letters rearranged gives 'echni'.
'echni' placed inside 'tc' is 'TECHNIC'.

'for' acts as a link.