Is it permissible to combine and shorten missed prayers after returning home due to being unable to perform them on time because clothes became soiled?

It is not permissible to delay prayer beyond its prescribed time. Allah has warned those who delay it, as He says: {So woe to those who pray [But] who are heedless of their prayer} [Al-Ma'un: 4-5]. It is permissible to combine and shorten prayers if the distance is a travel distance (83 km). However, if it is not, then it is obligatory to perform each prayer at its time, fully. Changing clothes is not an excuse for delaying prayer; one can take precautions and change in restrooms. If a place for purification is not available, then praying without purity at its prescribed time is better than delaying it, for prayer is more important than studying.