hesitate, shrink, awe
憚 centers on a fearful reluctance to act: hesitating or shrinking back from something daunting, often out of awe or deep respect.
憚 combines 忄 (heart/mind) with 單, which likely contributes the sound and may suggest something singular or weighty, giving the idea of a heart held back by awe or fear.
The heart radical 忄 beside 單 (which looks like a heavy, singular object) suggests a heart that hesitates and shrinks back when faced with something overwhelming.
For タン, imagine hesitating before a tan-colored giant: the tan color cues タン, and your heart shrinks back in awe.
reserve; modesty; hesitation; restraint
to hesitate; to have scruples; to be afraid of what others may think
unrestrained; unreserved; candid; frank
hesitation
with all due respect ...; I venture to say ...; Excuse me, but ...
thank you for your trouble; unfortunately ...
when you make a mistake, don't hesitate to correct it; do not delay in making amends for your wrongs