Cryptic crossword clue
T-shirts seen centrally in unit, available temporarily 2,4

The most common and most likely answer to this crossword clue is the 2 plus 4 letter word ON HIRE

I've seen this crossword clue in Financial Times
O
N
H
I
R
E

Buddy explains!

The straight part
We know that "available temporarily" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case available temporarily = on hire.
The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.
This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.

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